Note: Descriptions are shown in the official language in which they were submitted.
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DATE SEED POWDER AS A FLUID LOSS ADDITIVE FOR DRILLING
FLUIDS
CLAIM OF PRIORITY
[0001] This application claims priority to U.S. Patent Application No.
62/151,908 filed on April 23, 2015, the entire contents of which are hereby
incorporated by reference.
TECHNICAL FIELD
[0002] This disclosure relates to drilling fluids, e.g., water-based drilling
fluids.
BACKGROUND
[0003] A wellbore is a drilled hole or borehole formed through a subterranean
zone (e.g., a formation, multiple formations, or a portion of a formation) to
recover
hydrocarbons in the zone. To form the wellbore, a wellbore drilling system,
which can
include a drill bit, is lowered into the zone using drill strings. The drill
strings are
positioned in the wellbore to form an annulus between an outer wall of the
drill strings
and an inner wall of the wellbore. Drilling fluids (sometimes called drilling
muds) are
flowed from the surface through the drill strings to the drilling system. The
drilling
fluids exit the drilling system, e.g., through ports in the drill bits, and
flow through the
annulus formed between the drill strings and the wellbore to the surface. The
drilling
fluids serve several functions including, e.g., cooling the drill bits,
carrying cuttings to
the surface, and other functions. The drilling fluids can be water or oil-
based.
Because the subterranean zone can include porous rock, the drilling fluids can
sometimes be lost into the surround formation when flowing through the
annulus.
SUMMARY
[0004] This disclosure describes a fluid loss additive to control drilling
fluid
loss.
[0005] Certain aspects of the subject matter described here can be implemented
as a method. The method includes mixing a date seed powder and a homogenizer
with
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a fluid to provide a drilling fluid. The method further includes using the
drilling fluid
to drill a wellbore.
[0006] The fluid can include water. The drilling fluid can be a clay-free
drilling
fluid. The homogenizer can be at least one of psyllium husk (PHP), modified
starch
-- (MS) or xanthan gum (XC). The homogenizer can be present at a concentration
of
about 0.1% to about 5% weight/volume percent (w/v). The homogenizer can
include
xanthan gum and be present at a concentration of about 0.3% w/v. The
homogenizer
can include modified starch and be present at a concentration of about 0.3%
w/v. The
homogenizer can include psyllium husk and be present at a concentration of
about
-- 0.6% w/v. An alkaline salt can be added to the drilling fluid to increase
the pH of the
drilling fluid. The alkaline salt added can include sodium hydroxide. The
quantity of
alkaline salt added can be sufficient to increase the pH of the drilling fluid
to greater
than about 9. The quantity of alkaline salt added can be sufficient to
increase the pH
of the drilling fluid to between about 9 and about 10.5. The method can
further
-- include adding a defoamer to the drilling fluid. The quantity of defoamer
can be
sufficient to remove air bubbles from the drilling fluid with which the date
seed
powder is mixed. The date seed powder can be in a particulate form. For
example, the
date seed powder can have a size distribution of less than about 150 p.m. The
date seed
powder can have a size distribution ranging between about 50 p.m and about 150
p.m.
-- The date seed powder can be present at a concentration of about 1% w/v to
about 5%
w/v. For example, the date seed powder can be present at a concentration of
about 2%
w/v. To use the drilling fluid to drill a wellbore, the drilling fluid that
includes the
mixture can be flowed into the wellbore.
[0007] Certain aspects of the subject matter described here can be implemented
-- as a method. A wellbore can be drilled using a drilling fluid that includes
a date seed
powder, a homogenizer, and a fluid. The drilling fluid can be a clay-free
drilling fluid.
The fluid can include water. In some embodiments, the homogenizer includes at
least
one of psyllium husk, modified starch, or xanthan gum. The homogenizer can be
present at a concentration of about 0.1% to about 5% w/v. For example, the
-- homogenizer includes xanthan gum and is present at a concentration of about
0.3%
w/v. In some embodiments, the homogenizer includes modified starch and is
present
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at a concentration of about 0.3% w/v. In some embodiments, the homogenizer
includes psyllium husk and is present at a concentration of about 0.6% w/v.
[0008] In some embodiments, the method further includes adding an alkaline
salt to the drilling fluid to increase the pH of the fluid. The alkaline salt
can include
-- sodium hydroxide. The quantity of alkaline salt can be sufficient to
increase the pH of
the drilling fluid to greater than about 9. For example, the quantity of
alkaline salt can
be sufficient to increase the pH of the drilling fluid to between about 9 and
about 10.5.
[0009] In some embodiments, the method further includes adding a defoamer
to the drilling fluid. The quantity of defoamer can be sufficient to remove
air bubbles
-- from the fluid.
[0010] In some embodiments, the date seed powder is in particulate form. For
example, the date seed powder can have a size distribution of less than about
150 p.m.
The date seed powder can also have a size distribution ranging between 50 pm
and 150
p.m. In some embodiments, the date seed powder can be present at a
concentration of
-- about 1% w/v to about 5% w/v. For example, the date seed powder can be
present at a
concentration of about 2% w/v.
[0011] The present disclosure also relates to a drilling fluid. The drilling
fluid
includes a date seed powder, a homogenizer, and a fluid. The drilling fluid
can be a
clay-free drilling fluid. The fluid can include water. In some embodiments,
the
-- homogenizer includes at least one of psyllium husk, modified starch, or
xanthan gum.
The homogenizer can be present at a concentration of about 0.1% to about 5%
w/v.
For example, the homogenizer can include xanthan gum and be present at a
concentration of about 0.3% w/v. The homogenizer can include modified starch
and
be present at a concentration of about 0.3% w/v. In some embodiments, the
-- homogenizer includes psyllium husk and is present at a concentration of
about 0.6%
w/v.
[0012] In some embodiments, the drilling fluid includes adding an alkaline
salt
to the drilling fluid to increase the pH of the fluid. The alkaline salt can
include
sodium hydroxide. The quantity of alkaline salt can be sufficient to increase
the pH of
-- the drilling fluid to greater than about 9. For example, the quantity of
alkaline salt can
be sufficient to increase the pH of the drilling fluid to between about 9 and
about 10.5.
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[0013] In some embodiments, the drilling fluid further includes a defoamer.
The quantity of defoamer can be sufficient to remove air bubbles from the
fluid.
[0014] In some embodiments, the date seed powder is in particulate form. For
example, the date seed powder can have a size distribution of less than about
150 p.m.
The date seed powder can also have a size distribution ranging between 50 p.m
and 150
p.m. In some embodiments, the date seed powder can be present at a
concentration of
about 1% w/v to about 5% w/v. For example, the date seed powder can be present
at a
concentration of about 2% w/v.
[0015] The details of one or more implementations of the subject matter
to described in this specification are set forth in the accompanying
drawings and the
description below. Other features, aspects, and advantages of the subject
matter will
become apparent from the description, the drawings, and the claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] FIGS. 1A-1D are schematic diagrams of date seed powder preparation
systems.
[0017] FIG. 2 is a flowchart of an example process for preparing date seed
powder.
[0018] FIG. 3 is a flowchart of an example process for preparing drilling
fluid
that includes date seed powder.
[0019] FIG. 4 is a bar graph showing spurt loss behavior of example drilling
fluids.
[0020] FIG. 5 is a bar graph showing API fluid loss behavior of example
drilling fluids.
[0021] FIG. 6 is a bar graph showing mud cake quality and thickness of
example drilling fluids.
[0022] FIG. 7 is a bar graph showing spurt loss behavior of example drilling
fluids evaluated under High Temperature / High Pressure (HTHP) conditions.
[0023] FIG. 8 is a bar graph showing fluid loss behavior of example drilling
fluids evaluated under HTHP conditions.
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[0024] FIG. 9 is a bar graph showing mud cake thickness of example drilling
fluids evaluated under HTHP conditions.
[0025] FIG. 10 is a flowchart of an example process for using drilling fluid
that
includes date seed powder to drill a wellbore.
[0026] Like reference numbers and designations in the various drawings
indicate like elements.
DETAILED DESCRIPTION
[0027] This disclosure describes date seed powder as a fluid loss additive for
drilling fluids. In the course of drilling a well, water-based or oil-based
drilling fluids
to are pumped
from the surface to the bottom of the hole and then brought back to the
surface by using appropriate rig hydraulics and mud pumps. As the subsurface
zone is
porous and permeable, drilling fluids can be lost into the zone. Excessive
loss of
alkaline mud filtrate of a drilling mud to the near wellbore formation can
cause
swelling and dispersion of clays in the formations leading to borehole
instability
problems. The excessive loss of mud filtrate can also cause severe formation
damage
while drilling the subterranean zone. Moreover, the loss of drilling fluids
beyond an
acceptable range as a result of the escape of water to the porous formations
can change
the rheological and thixotropic properties of the drilling fluids. Excessive
dewatering
of drilling fluid in differential sticking prone, high permeable zones can
create a thick
mud cake on the borehole wall. The alteration of the functional capability of
drilling
muds due to excessive dewatering can lead to different types of costly
drilling
problems such as poor hole cleaning, hole fill up, pipe sticking, induced loss
of
circulation, high surge and swabbing effect while making a trip, or other
drilling
problems. At least for these reasons, control of the fluid loss potential of
drilling fluids
while making a borehole is important both for drilling and production phases
of oil and
gas exploration and exploitation.
[0028] Fluid loss additives are used in the formulation of drilling and
completion fluids to control the loss of fluid to the surrounding formations
within an
acceptable range, e.g., less than about 15 cc/30 minutes in standard the
American
Petroleum Institute (API) test condition (e.g., API Recommended Practice 13B-1
and
13B-2). Various organic and inorganic polymers and also plant-based materials
can be
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used as fluid loss control additives to maintain the quality and functional
ability of the
drilling fluids. Some synthetic polymeric additives are not easily
biodegradable and
thus can cause some environmental problems, especially in sensitive
environments.
[0029] This disclosure describes the application of date seed powder as a
fluid
loss additive or fluid loss additive supplement for water-based drilling
fluids to prevent
excessive loss of the drilling fluid during wellbore formation. The date seed
power
can be an ecofriendly and easily biodegradable natural fluid loss additive
suitable for
application in sensitive environments, e.g., offshore drilling environments.
As
described below, the date seed powder can be formed from dates into particles
having
a size distribution ranging between 50 p.m and 150 p.m. Also as described
below, API
fluid loss tests and High Temperature / High Pressure (HTHP) tests at 212 F
and 500
psi overbalance pressure indicate that the presence of date seed powder can
significantly reduce API and HTHP fluid loss behavior of clay free systems.
Implementing date seed powder as a fluid loss additive enables reusing waste
by-
product of the date palm industry. Date seed powder can serve as a viable
alternative
to other fluid loss additives that may be difficult to manufacture or
expensive to
procure (or both).
[0030] FIGS. 1A-1D are schematic diagrams of date seed powder preparation
systems. FIG. 2 is a flowchart of an example process 200 for preparing date
seed
powder. At 202, flesh from dates is peeled to isolate the seeds. At 204, the
isolated
seeds are washed, e.g., with fresh water or other fluid, to remove sticky
flesh from the
seed. At 206, the seeds are roasted. For example, FIG. 1A shows a roaster 102,
such
as a pan or utensil with a flat surface, to roast the seeds. Roasting the
seeds can
remove any excessive moisture in the seeds, which, in turn, can make the seeds
more
brittle and consequently easily grindable. At 208, the roasted seeds are
cooled, e.g., to
room temperature. At 210, the roasted, cooled seeds are ground. For example,
FIG.
1B shows a grinder 104 to grind a quantity (e.g., 100 g or other quantity) of
the seeds
into powder that includes particles of different sizes in the micrometer
range. The
grinder 104 can be a programmable grinding machine that can grind the seeds
for a
duration (e.g., about 30 to 40 minutes) in multiple steps. At 212, the ground
seeds can
be sieved. For example, FIG. 1C shows a sieve system 106 that can include one
or
more sieves having meshes of different sizes. Passing the ground seeds through
the
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sieves in the sieve system 106 can allow separating the ground seeds into
particles of
sizes that correspond to the sizes of the meshes. In this manner, in some
implementations, date seed powder having sizes of less than 150 p.m can be
obtained.
Drilling Fluids Including Date Seeds
[0031] The present disclosure relates to a drilling fluid. The drilling fluid
includes a date seed powder, a homogenizer, and a fluid.
[0032] The drilling fluid can be a clay-free drilling fluid. The fluid can
include
water. For example, the drilling fluid can be a clay-free, water-based
drilling fluid.
The water can include fresh water, brine, produced water, flowback water,
brackish
water, seawater, and mixtures thereof
[0033] As used herein, the term "clay-free" refers to a drilling fluid
formulated
without addition of any clays to the drilling fluid. During drilling, such
"clay-free"
drilling fluids may acquire clays and lignites from the formation or from
mixing with
recycled fluids containing clays and lignites.
[0034] In some embodiments, the date seed powder is in particulate form. For
example, the date seed powder can have a size distribution of less than about
150 p.m.
The date seed powder can also have a size distribution ranging between 50 pm
and 150
pm.
[0035] As used herein, the term "about" can allow for a degree of variability
in
a value or range, for example, within 10%, within 5%, or within 1% of a stated
value
or of a stated limit of a range.
[0036] In some embodiments, the date seed powder is present at a
concentration of about 1% w/v to about 10% w/v, about 1% w/v to about 5% w/v,
or
about 1% w/v to about 3% w/v. For example, the date seed powder can be present
at a
concentration of about 10% w/v, 7%, 5%, 3%, 2%, or about 1% w/v.
[0037] As used herein "w/v" refers to the grams of a component per 100 mL of
fluid. For example, 6 g of date seed powder in 350 mL of fluid would be
present in the
fluid at a concentration of about 1.7% w/v.
[0038] In some embodiments, the homogenizer includes at least one of
psyllium husk, modified starch, or xanthan gum. The homogenizer can also
include a
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polysaccharide; a biopolymers or derivatives thereof that contain one or more
of these
monosaccharide units: galactose; mannose; glucoside; glucose; xylose;
arabinose;
fructose; glucuronic acid; or pyranosyl sulfate. Examples of suitable
polysaccharides
include, but are not limited to, guar gums (e.g., hydroxyethyl guar,
hydroxypropyl
guar, carboxymethyl guar, carboxymethylhy
droxy ethyl guar, and
carboxymethylhydroxypropyl guar ("CMHPG")); cellulose derivatives (e.g.,
hydroxyethyl cellulose, carboxyethylcellulose, carboxymethylcellulose, and
carboxymethylhy droxy ethylcellulose); scleroglucan; succinogly can; diutan;
or
combinations thereof
[0039] The homogenizer can be present at a concentration of about 0.1% to
about 10% w/v, about 0.1% to about 8 % w/v, about 0.1% to about 6% w/v, about
0.1% to about 5% w/v, about 0.1% to about 4% w/v, about 0.1% to about 3% w/v,
about 0.1% to about 2% w/v, or about 0.1% to about 1% w/v. For example, the
homogenizer can be present at a concentration of about 10% w/v, 8%, 6%, 5%,
4%,
3%, 2%, 1%, 0.9%, 0.6%, or about 0.3% w/v. The homogenizer can include xanthan
gum and be present at a concentration of about 0.1% to about 2% w/v. The
homogenizer can include xanthan gum and be present at a concentration of about
0.3%
w/v. For example, the drilling fluid can include about 1 g of xanthan gum per
350 mL
of fluid. The homogenizer can include modified starch and be present at a
concentration of about 0.1% to about 2% w/v. The homogenizer can include
modified
starch and be present at a concentration of about 0.3% w/v. For example, the
drilling
fluid can include about 1 g of modified starch per 350 mL of water. The
homogenizer
can include psyllium husk and be present at a concentration of about 1% to
about 3%
w/v. The homogenizer can include psyllium husk and be present at a
concentration of
about 0.6% w/v. For example, the drilling fluid can include about 1 g of
psyllium husk
per 175 mL of fluid.
[0040] In some embodiments, the drilling fluid includes an alkaline salt,
which
can increase the pH of the drilling fluid. The alkaline salt can include
sodium
hydroxide, potassium hydroxide, magnesium hydroxide, calcium hydroxide, sodium
silicate, sodium carbonate, magnesium oxide, and combinations thereof In some
embodiments, the alkaline salt includes sodium hydroxide (NaOH). The quantity
of
alkaline salt can be sufficient to increase the pH of the drilling fluid to a
pH of greater
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than about 9. For example, the quantity of alkaline salt can be sufficient to
increase
the pH of the drilling fluid to a pH of between about 9 and about 10.5.
[0041] In some embodiments, the drilling fluid further includes a defoamer.
The quantity of defoamer can be sufficient to remove air bubbles from the
fluid. For
example, about two to three drops of defoamer can be added per 350 mL of the
fluid.
[0042] The drilling fluid can additionally include one or more additives
including a surfactant (e.g., a foamer, a wetting agent, a detergent, a
lubricant, or a
corrosion inhibitor), a water softener, an oxygen scavenger, a biocide, a
corrosion
inhibitor, and a weighting agent.
Preparation of Drilling Fluids Including Date Seeds
[0043] Also, provided in this disclosure is a method for preparing a drilling
fluid. The method includes mixing a date seed powder and a homogenizer with a
fluid
to provide a drilling fluid.
[0044] The drilling fluid can be a water-based drilling fluid. The drilling
fluid
can be a clay-free drilling fluid. For example, the drilling fluid can be a
clay-free,
water-based drilling fluid. The water can include fresh water, brine, produced
water,
flowback water, brackish water, seawater, and mixtures thereof
[0045] In some embodiments, the date seed powder is in particulate form. For
example, the date seed powder can have a size distribution of less than about
150 p.m.
The date seed powder can also have a size distribution ranging between 50 p.m
and 150
pm.
[0046] In some embodiments, the date seed powder is present at a
concentration of about 1% w/v to about 10% w/v, about 1% w/v to about 5% w/v,
or
about 1% w/v to about 3% w/v. For example, the date seed powder can be present
at a
concentration of about 10% w/v, 7%, 5%, 3%, 2%, or about 1% w/v
[0047] The homogenizer can be at least one of psyllium husk (PHP), modified
starch (MS) or xanthan gum (XC). In some embodiments, the homogenizer includes
at
least one of psyllium husk, modified starch, or xanthan gum. The homogenizer
can
also include at least a polysaccharide; a biopolymers or derivatives thereof
that contain
one or more of these monosaccharide units: galactose; mannose; glucoside;
glucose;
xylose; arabinose; fructose; glucuronic acid; or pyranosyl sulfate. Examples
of suitable
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polysaccharides include, but are not limited to, guar gums (e.g., hydroxyethyl
guar,
hydroxypropyl guar, carboxymethyl guar, carboxymethylhydroxyethyl guar, and
carboxymethylhydroxypropyl guar ("CMHPG")); cellulose derivatives (e.g.,
hydroxyethyl cellulose, carboxyethylcellulose, carboxymethylcellulose, and
carboxymethylhy droxy ethylcellulose); scleroglucan; succinogly can; diutan;
and
combinations thereof
[0048] The homogenizer can be present at a concentration of about 0.1% to
about 10% w/v, about 0.1% to about 8 % w/v, about 0.1% to about 6% w/v, about
0.1% to about 5% w/v, about 0.1% to about 4% w/v, about 0.1% to about 3% w/v,
about 0.1% to about 2% w/v, or about 0.1% to about 1% w/v. For example, the
homogenizer can be present at a concentration of about 10% w/v, 8%, 6%, 5%,
4%,
3%, 2%, 1%, 0.9%, 0.6%, or about 0.3% w/v. The homogenizer can include xanthan
gum and be present at a concentration of about 0.1% to about 2% w/v. The
homogenizer can include xanthan gum and be present at a concentration of about
0.3%
w/v. For example, the drilling fluid can include about 1 g of xanthan gum per
350 mL
of fluid. The homogenizer can include modified starch and be present at a
concentration of about 0.1% to about 2% w/v. The homogenizer can include
modified
starch and be present at a concentration of about 0.3% w/v. For example, the
drilling
fluid can include about 1 g of modified starch per 350 mL of water. The
homogenizer
can include psyllium husk and be present at a concentration of about 1% to
about 3%
w/v. The homogenizer can include psyllium husk and be present at a
concentration of
about 0.6% w/v. For example, the drilling fluid can include about 1 g of
psyllium husk
per 175 mL of fluid.
[0049] The method can further include adding an alkaline salt to increase the
pH of the drilling fluid. The alkaline salt can include sodium hydroxide,
potassium
hydroxide, magnesium hydroxide, calcium hydroxide, sodium silicate, sodium
carbonate, magnesium oxide, and combinations thereof In some embodiments, the
alkaline salt added includes sodium hydroxide. The quantity of alkaline salt
added can
be sufficient to increase the pH of the drilling fluid to a pH of greater than
about 9.
The quantity of alkaline salt added can be sufficient to increase the pH of
the drilling
fluid to a pH of between about 9 and about 10.5.
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[0050] The method can further include adding a defoamer to the drilling fluid.
The quantity of defoamer can be sufficient to remove air bubbles from the
drilling
fluid with which the date seed powder is mixed.
[0051] To use the drilling fluid to drill a wellbore, the drilling fluid can
be
flowed into the wellbore.
[0052] FIG. 3 is a flowchart of an example process 300 for preparing drilling
fluid that includes date seed powder. At 302, a quantity of date seed powder
is mixed
with a volume of water. At 304, a homogenizer is added to the mixture to
homogeneously suspend the date seed powder in the drilling fluid. The
homogenizer
to can be, for example, psyllium husk (PHP), modified starch (MS) or
xanthan gum
(XC). A quantity of the homogenizer added to the mixture can be sufficient to
increase the viscosity of the water such that the quantity of date seed powder
can be
homogenously distributed across the volume of water. At 306, an alkaline salt
(e.g.,
sodium hydroxide or other alkaline salt) is added to adjust the pH of the
drilling fluid
such that the drilling fluid is alkaline. Examples of alkaline salts include
sodium
hydroxide, potassium hydroxide, magnesium hydroxide, calcium hydroxide, sodium
silicate, sodium carbonate, or other alkaline salts. At 308, the mixture can
be blended,
e.g., by using a high speed mixer. In case of excessive foaming, at 310,
defoamer can
be added to remove air bubbles. Several water-based drilling fluids including
date
seed powder were formulated by implementing the process 300 as shown in tables
below.
Method of drilling a wellbore
[0053] Also provided in this disclosure is a method of drilling a wellbore.
The
wellbore is drilled using a drilling fluid that includes a date seed powder, a
homogenizer, and a fluid.
[0054] The drilling fluid can be a clay-free drilling fluid. The fluid can
include
water. For example, the drilling fluid can be a clay-free, water-based
drilling fluid.
The water can include fresh water, brine, produced water, flowback water,
brackish
water, seawater, and mixtures thereof In some embodiments, water, including
any
dissolved materials therein, is present in the drilling fluids in an amount in
the range
from about 50% to 100% by volume of the drilling fluid.
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[0055] In some embodiments, the date seed powder is in particulate form. For
example, the date seed powder can have a size distribution of less than about
150 p.m.
The date seed powder can also have a size distribution ranging between 50 pm
and 150
pm.
[0056] In some embodiments, the date seed powder is present at a
concentration of about 1% w/v to about 10% w/v, about 1% w/v to about 5% w/v,
or
about 1% w/v to about 3% w/v. For example, the date seed powder can be present
at a
concentration of about 10% w/v, 7%, 5%, 3%, 2% or about 1% w/v.
[0057] The drilling fluid can be adapted to be a carrier fluid for
particulates.
-- For example, during drilling, rock cuttings can be carried uphole by the
drilling fluid
and flowed out of the wellbore. Rock cuttings can range in size from silt-
sized
particles to chunks measured in centimeters. The rock cuttings can have
specific
gravity greater than 2. These high-density cuttings have a tendency to
separate from
water or oil very rapidly. A homogenizer can be used to increase the ability
of a fluid
-- to suspend and carry a particulate material in a well fluid (e.g., the date
seed powder).
[0058] In some embodiments, the homogenizer includes at least one of
psyllium husk, modified starch, or xanthan gum. The homogenizer can also
include at
least a polysaccharide; a biopolymers or derivatives thereof that contain one
or more of
these monosaccharide units: galactose; mannose; glucoside; glucose; xylose;
-- arabinose; fructose; glucuronic acid; or pyranosyl sulfate. Examples of
suitable
polysaccharides include, but are not limited to, guar gums (e.g., hydroxyethyl
guar,
hydroxypropyl guar, carboxymethyl guar, carboxymethylhydroxyethyl guar, and
carboxymethylhydroxypropyl guar ("CMHPG")); cellulose derivatives (e.g.,
hydroxyethyl cellulose, carboxyethylcellulose, carboxymethylcellulose, and
-- carboxymethylhydroxy ethylcellulose); scleroglucan; s uccinogly can;
diutan; and
combinations thereof In some embodiments, the homogenizer includes at least
one of
psyllium husk, modified starch, or xanthan gum.
[0059] The homogenizer can be present at a concentration of about 0.1% to
about 5% w/v. For example, the homogenizer includes xanthan gum and is present
at
-- a concentration of about 0.3% w/v. In some embodiments, the homogenizer
includes
modified starch and is present at a concentration of about 0.3% w/v. In some
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embodiments, the homogenizer includes psyllium husk and is present at a
concentration of about 0.6% w/v.
[0060] The homogenizer can be present at a concentration of about 0.1% to
about 10% w/v, about 0.1% to about 8 % w/v, about 0.1% to about 6% w/v, about
0.1% to about 5% w/v, about 0.1% to about 4% w/v, about 0.1% to about 3% w/v,
about 0.1% to about 2% w/v, or about 0.1% to about 1% w/v. For example, the
homogenizer can be present at a concentration of about 10% w/v, 8%, 6%, 5%,
4%,
3%, 2%, 1%, 0.9%, 0.6%, or about 0.3% w/v. The homogenizer can include xanthan
gum and be present at a concentration of about 0.1% to about 2% w/v. For
example,
the homogenizer can include xanthan gum and be present at a concentration of
about
0.3% w/v. The homogenizer can include modified starch and be present at a
concentration of about 0.1% to about 2% w/v. For example, the homogenizer can
include modified starch and be present at a concentration of about 0.3% w/v.
The
homogenizer can include psyllium husk and be present at a concentration of
about 1%
to about 3% w/v. For example, the homogenizer can include psyllium husk and be
present at a concentration of about 0.6% w/v.
[0061] In some embodiments, the method further includes adding an alkaline
salt to the drilling fluid to increase the pH of the fluid. The alkaline salt
can include
sodium hydroxide, potassium hydroxide, magnesium hydroxide, calcium hydroxide,
sodium silicate, sodium carbonate, magnesium oxide, and combinations thereof
In
some embodiments, the alkaline salt includes sodium hydroxide. The quantity of
alkaline salt can be sufficient to increase the pH of the drilling fluid to a
pH of greater
than about 9. For example, the quantity of alkaline salt can be sufficient to
increase
the pH of the drilling fluid to a pH of between about 9 and about 10.5.
[0062] In some embodiments, the method further includes adding a defoamer
to the drilling fluid. The quantity of defoamer can be sufficient to remove
air bubbles
from the fluid.
[0063] The drilling fluid can additionally include one or more additives
including a surfactant (e.g., a foamer, a wetting agent, a detergent, a
lubricant, or a
corrosion inhibitor), a water softener, an oxygen scavenger, a biocide, a
corrosion
inhibitor, and a weighting agent.
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[0064] Examples of weighting agents are water-soluble salts, including
inorganic salts. The weighting agent can be dissolved in the fluid (e.g.,
water). Salts
can be added to a water source, for example, to provide a brine, and a
resulting drilling
fluid, having a desired density. Salts can also be included for reasons
related to
compatibility of the drilling fluid with the formation and formation fluids.
Evaluation of Drilling Fluids
[0065] Each drilling fluid prepared by implementing process 300 described
above was evaluated. In some implementations, each drilling fluid was
evaluated by
performing one or more of spurt loss tests, fluid loss tests, mud cake
thickness tests, or
to filtration time tests under API conditions. In some implementations, one
or more of
the spurt loss tests, fluid loss tests, mud cake thickness tests, or
filtration tests were
performed under HTHP conditions. Drilling fluids were also prepared without
date
seed powder and evaluated under the API conditions and the HTHP conditions. A
comparison the evaluation results revealed that drilling fluids that include
date seed
powder show superior fluid loss prevention relative to drilling fluids that do
not
include date seed powder.
[0066] The compositions of several drilling fluids are described with
reference
to tables below. Each drilling fluid can be manufactured by implementing all
or
portions of process 300 described above.
EXAMPLES
Examples I and II
[0067] The composition of a first drilling fluid (Example I) and a second
drilling fluid (Example II) are shown in Table 1. As shown below, Example I
does not
include any date seed powder and Example II includes a quantity of date seed
powder.
In addition, each of Example I and Example II uses 1 g of xanthan gum (XC) as
the
homogenizer to increase the viscosity of water.
Drilling Fluid Components Example I Example II
Water (mL) 350 350
PHP (g) 0 0
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XC (g) 1 1
MS (g) 0 0
Date Seed Powder (g) 0 6
NaOH (mL) As required to raise pH to As required to raise pH
to
10
Defoamer (cc) 2 to 3 drops as required 2 to 3 drops as
required
Table 1. Composition of Example I and Example II drilling fluids.
Examples III and IV
[0068] The composition of a third drilling fluid (Example III) and a fourth
drilling fluid (Example IV) are shown in Table 2. As shown below, Example III
does
5 not include any date seed powder and Example IV includes a quantity of
date seed
powder. In addition, Example III uses 6 g of MS as the homogenizer, and
Example IV
uses 1 g of XC as the homogenizer to increase the viscosity of water.
Drilling Fluid Components Example III Example IV
Water (mL) 350 350
PHP (g) 0 0
XC (g) 0 1
MS (g) 6 0
Date Seed Powder (g) 0 6
NaOH (mL) As required to raise pH to As required to raise pH
to
10 10
Defoamer (cc) 2 to 3 drops as required 2 to 3 drops as
required
Table 2. Composition of Example III and Example IV drilling fluids.
Examples V and VI
10 [0069] The composition of a fifth drilling fluid (Example V) and a sixth
drilling fluid (Example VI) are shown in Table 3. As shown below, Example V
does
not include any date seed powder and Example VI includes a quantity of date
seed
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powder. In addition, each of Example V and Example VI uses 2 g of psyllium
husk
(PHP) as the homogenizer to increase the viscosity of water.
Drilling Fluid Components Example V Example VI
Water (mL) 350 350
PHP (g) 2 2
XC (g) 0 0
MS (g) 6 0
Date Seed Powder (g) 0 6
NaOH (mL) As required to raise pH to As required to raise pH
to
10
Defoamer (cc) 2 to 3 drops as required 2 to 3 drops as required
Table 3. Composition of Example V and Example VI drilling fluids.
[0070] Each of Examples I ¨ VI described above is clay-free. The water used
5 in each of Examples I ¨ VI is fresh water. Examples I ¨ VI, described
above, were
evaluated for fluid loss behavior. Examples VII ¨ X, described below, were
evaluated
for fluid loss behavior under HTHP conditions.
Examples VII, VIII, IX, and X
[0071] Compositions of a seventh drilling fluid (Example VII), an eighth
10 drilling fluid (Example VIII), a ninth drilling fluid (Example IX), and
a tenth drilling
fluid (Example X) are shown in Table 4. Examples VII and VIII were
manufactured
using fresh water, and Examples IX and X were manufactured using red sea
water.
Each of Examples VII, VIII, IX and X uses 2 g of PHP as a homogenizer to
increase
the viscosity of water. In addition, Examples VII and IX did not include any
date seed
powder, and Examples VIII and X included a quantity of date seed powder. Each
of
Examples VII, VIII, IX and X is clay-free.
Drilling Fluid Example VII Example VIII Example IX Example X
Components
Fresh water (ml) 350 350
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Red sea water (m1) -- 350 350
PHP (g) 2 2 2 2
DSP (g) 0 6 0 6
NaOH (m1) As required to As required to As required to As required to
raise pH to 10 raise pH to 10 raise pH to 10 raise pH to 10
Defoamer (cc) 2 to 3 drops as 2 to 3 drops as 2 to 3 drops as 2 to 3
drops as
required required required required
Table 4. Composition of Examples VII, VIII, IX and X drilling fluids.
Results
[0072] The API filtration properties of Examples I ¨ VI were measured. Table
below shows the experimental results of API tests.
Drilling Fluid API Test (Room temperature & 100 psi overbalance pressure)
Spurt loss (cc) Fluid loss (cc) Mud cake Filtration time
thickness (mm) (min)
Example 1 90 175 0.397 30
Example II 9 31 0.794 30
Example III 45 86 1.59 30
Example IV 24 35 0.794 30
Example V 2 18 0.794 30
Example VI 1 12 0.794 30
5 Table 5. API fluid loss
test results for example drilling fluids.
[0073] FIG. 4 is a bar graph 400 showing spurt loss behavior of example
drilling fluids. Comparison of spurt loss behavior of clay-free Example I and
Example
II indicates 90 cc API spurt loss for Example I, which does not include date
seed
powder, but only 9 cc API spurt loss for Example II which includes date seed
powder.
This is about 90% drop of API spurt loss due to the presence of date seed
powder.
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This result proves the application and suitability of date seed powder as
fluid loss
additive or additive supplement for water-based drilling fluid systems.
[0074] Comparison of the spurt loss behavior of clay-free Example III, which
is a conventional fluid loss additive, with Example IV, which contains date
seed
powder, also reveals improved spurt loss behavior for the drilling fluid which
includes
date seed powder. The spurt loss behavior for Example IV is about 40% lower
relative
to that for Example III. This result again supports the application of date
seed powder
as a fluid loss additive to control the fluid loss behavior of water-based
muds.
[0075] Comparison of the spurt loss behavior of clay-free Example V, which
1() does not
include date seed powder, and Example VI, which includes date seed powder,
revealed that the spurt loss behavior of Example VI is about 50% lower than
that of
Example V, although the spurt loss behavior of both examples is low (i.e.,
less than or
equal to about 2 cc). This result further proves the suitability of date seed
powder as a
fluid loss additive for water-based mud systems.
[0076] FIG. 5 is a bar graph 500 showing API fluid loss behavior of example
drilling fluids. Comparison of fluid loss behavior of clay-free Example I and
Example
II indicates 175 cc API fluid loss for Example I, which does not include date
seed
powder, but only 31 cc API fluid loss for Example II, which includes date seed
powder. This is about 82% drop of fluid loss due to the presence of date seed
powder.
This result proves the application and suitability of date seed powder as
fluid loss
additive or additive supplement for water-based drilling fluid systems.
[0077] Comparison of the fluid loss behavior of clay-free Example III, which
is a conventional fluid loss additive, with Example IV, which contains date
seed
powder, also reveals improved fluid loss behavior for the drilling fluid which
includes
date seed powder. This result again supports the application of date seed
powder as a
fluid loss additive to control the fluid loss behavior of water-based muds.
[0078] Comparison of the fluid loss behavior of clay-free Example V, which
does not include date seed powder, and Example VI, which includes date seed
powder,
revealed that the fluid loss behavior of Example VI is about 50% lower than
that of
Example V, which does not include date seed powder. This result further proves
the
suitability of date seed powder as a fluid loss additive for water-based mud
systems.
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The line shown in FIG. 5 indicates the API recommended maximum fluid loss
value
(which is less than 15cc/30 minutes filtration time) for water-based drilling
fluid
system. The presence of date seed powder in Examples II, IV and VI reduced the
filtration behavior of the system to 25% below the API recommended value. The
results again demonstrate the suitability of the date seed powder as a fluid
loss additive
or additive supplement for water-based drilling fluid systems.
[0079] FIG. 6 is a bar graph 600 showing mud cake quality and thickness of
example drilling fluids. Comparison of mud cake thickness of clay-free Example
I and
Example II indicates formation of very thin but poor quality mud cake for
Example I,
to which does not include date seed powder, but a thin and good quality mud
cake for
Example II, which includes date seed powder. The quality of mud cake in
Example II
is reflected by the significant drop in API spurt and fluid loss behavior of
Example II.
Similar results are observed for Example IV and Example VI relative to Example
III
and Example V, respectively. The deposition of good quality and thin mud cakes
in
the presence of date seed powder as fluid loss additive or additive supplement
will
play a positive role in reducing the scope of differential sticking problems
in a
differential sticking prone borehole environments. It will also play a
positive role in
reducing other mud cake related drilling problems. For these reasons, the date
palm
industry by-product 'date seed' has a high potential to use as a locally
available raw
materials for development of additives/products for oil and gas fields
application.
[0080] Table 6 shows the experimental results of the HTHP tests.
Drilling Fluid HTHP test (100 C and 500 psi overbalance pressure)
Spurt loss (cc) Fluid loss (cc) Mud cake thickness
(mm)
Example VII 8.4 76.4 1.984
Example VIII 4 30 1.588
Example IX 6 47 1.984
Example X 4.53 21 1.984
Table 6. HTHP test results for example drilling fluids.
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[0081] FIG. 7 is a bar graph 700 showing spurt loss behavior of example
drilling fluids evaluated under HTHP conditions. Comparison of spurt loss
behavior
of clay-free Example VII and Example VIII indicates 8.4 cc HTHP spurt loss in
Example VII, which does not include date seed powder, but only 4 cc HTHP spurt
loss
in Example VIII, which includes date seed powder. This is more than 50% drop
of
HTHP fluid loss in Example VIII relative to Example VII due to the presence of
date
seed powder. Comparison of spurt loss behavior of clay-free Example IX and
Example X reveal a similar reduction in spurt loss in the presence of date
seed powder,
thereby supporting the application of date seed powder as a fluid loss
additive or
additive supplement for both fresh and sea-water based drilling fluid systems.
[0082] FIG. 8 is a bar graph 800 showing fluid loss behavior of example
drilling fluids evaluated under HTHP conditions. Comparison of fluid loss
behavior of
clay-free Example VII and Example VIII indicates 76.4 cc HTHP fluid loss in
Example VII, which does not include date seed powder, but only 30 cc HTHP
fluid
loss in Example VIII, which includes date seed powder. This is more than 60%
drop
of HTHP fluid loss in Example VIII relative to Example VII due to the presence
of
date seed powder. Comparison of fluid loss behavior of clay-free Example IX
and
Example X reveal a similar reduction in fluid loss in the presence of date
seed powder,
thereby supporting the application of date seed powder as a fluid loss
additive or
additive supplement for both fresh and sea-water based drilling fluid systems.
[0083] FIG. 9 is a bar graph 900 showing mud cake thickness of example
drilling fluids evaluated under HTHP conditions. Comparison of mud cake
thickness
of Examples VII, VIII, IX, and X indicates the formation of very thin mud
cakes both
in the absence and presence of the date seed powder. This indicates no unusual
effect
of the date seed powder in the physical behavior, i.e., thickness of the mud
cakes.
However, the drilling fluids containing no date seed powder (i.e., Examples
VII and
IX) produced poor quality mud cakes due to the lack of formation of a well
dispersed
and tough mud cake while conducting the filtration test relative to the
drilling fluids
containing date seed powder (i.e., Examples VIII and X). The superior quality
of mud
cake formed when using drilling fluids that contain date seed powder is
reflected by
the well dispersed and homogeneous nature of the mud cakes along with a
significant
drop of HTHP spurt and fluid loss behavior of the drilling fluids. The
deposition of
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good quality and thin mud cakes in the presence of date seed powder can play a
positive role in reducing the scope of differential sticking in a differential
sticking
prone borehole environments.
[0084] FIG. 10 is a flowchart of an example process 1000 for using drilling
fluid that includes date seed powder to drill a wellbore. At 1002, date seed
powder is
mixed to drilling fluid. For example, date seed powder can be mixed to
drilling fluid
to manufacture any of Examples II, IV, VI, VIII or X described above.
Alternatively,
other quantities of date seed powder can be mixed with other volumes of other
drilling
fluids to manufacture drilling fluids different from Examples II, IV, VI, VIII
or X
described above. At 1004, the drilling fluid including the date seed powder
can be
used to drill a wellbore. For example, the drilling fluid can be pumped into a
drill
string from the surface of the wellbore, through the drill bits in the
drilling system
positioned in the wellbore, through the annulus formed between the drill
string and the
wellbore, and out of the surface of the wellbore. In some implementations, 6
grams of
date seed powder can be mixed with 350 ml of water to produce a homogenous
slurry.
[0085] Particular implementations of the subject matter have been described.
The sequence of processes described here can be different from the sequence
shown
and described with reference to the flowcharts. In some implementations, one
or more
of the processes shown in the sequence can be omitted. For example, the
roasted seeds
can be ground prior to or without cooling the seeds. In another example, the
alkaline
salt can be added before the homogenizer. In a further example, the
homogenizer and
the salt can be added to the water before the date seed powder. Other
implementations
are within the scope of the following claims.
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